Draw up some graphics: dots, the board, the ghosts, your Wakka Wakka toon that you control.
Sounds: You need that wakka wakka sound or it's not packman.
Enemies need to chase you, so you need to look into some A.I to get them to chase you.
As you eat up pellets, you need a score system adding up the points. Code that up.
Super saiyan pellets need to be added to make you invincible and change the A.I to fear you and run away. Don't forget the music has to change to make you feel like a god against those ghosts.

O.o I want to do this now...damn you. I'll do the graphics! Someone code it.